1. Technical Field
The present invention relates to controlling display of a virtual object that is virtually displayed in a virtual reality space and, in particular, to improving visibility of a real object whose state has changed in a real space when displaying a virtual object superimposed on the real object.
2. Background Art
Conventionally, in a virtual reality space that is realized by using a head mounted display or the like, a virtually displayed object (hereinafter, referred to as a virtual object) may be displayed superimposed on an object existing in a real space (hereinafter, referred to as a real object). In such situations, as a user attempts to make some kind a move with respect to the real object, the user's field of view of the real object may sometimes become blocked by a virtual object displayed in front of the real object from the perspective of the user, in which case the real object becomes unviewable from the user.
FIGS. 18 and 19 are diagrams showing examples in which a real object and a virtual object are displayed superimposed in a virtual reality space. In FIG. 18, from the perspective of a user A201, a virtual object group A202 made up of a plurality of virtual objects is displayed superimposed in front of a mobile phone A203 that is a real object. In this case, the virtual object group A202 is a collection of transparent or non-transparent virtual objects. In FIG. 19 also, from the perspective of a user B211, a virtual object group B212 is displayed superimposed in front of a mobile phone B213 in a similar manner to FIG. 18.
FIG. 18 shows a case where a voice call is received by the mobile phone A203, and FIG. 19 shows a case where an e-mail is received by a mobile phone. A difference between FIGS. 18 and 19 is in moves that a user makes based on judgments made by the user on what has been received by the mobile phone. In FIG. 18, since a voice call has been received by the mobile phone A203, the user A201 makes a move of reaching out a hand toward the mobile phone A203. In other words, in the case where a voice call is received by the mobile phone A203, since the mobile phone A203 must be picked up immediately, the user A201 makes a move of reaching out a hand.
In this case, if the virtual object group A202 is displayed in front of the mobile phone A203, a problem arises in that the mobile phone A203 becomes hidden by the virtual object group A202 and the user A201 cannot pick up the mobile phone A203 with ease. Therefore, in this case, by hiding the virtual object group A202, the user is able to pick up the mobile phone A203 with ease.
On the other hand, in FIG. 19, since an e-mail has been received by the mobile phone B213, the user B211 makes a move of turning around to the mobile phone B213. In other words, in a case where an e-mail is received by the mobile phone B213, there is no need to immediately pick up the mobile phone B213. Therefore, the user B211 simply makes a move of turning around to the mobile phone B213 and does not make a move of picking up the mobile phone B213 as is the case where a voice call is received.
In this case, since the user B211 need not pick up the mobile phone B213, the virtual object group B212 does not pose a problem for the user B211 even when displayed in front of the mobile phone B213. Moreover, by leaving the virtual object group B212 displayed, a sense of presence that is unique to an augmented reality space can be imparted to the user B211.
As described above, depending on a state of a real object and a move made by a user with respect to the state, there are cases where it is better to hide the virtual object groups A202 and B212 and cases where it is better to display the virtual object groups A202 and B212.
Techniques utilizing a virtual reality space are adopted in medicine or the like. For example, Patent Document 1 discloses an image processing device which displays a surgical site in a virtual reality space, wherein a site included in a field-of-view secured region which exists between a user's field of view and the surgical site is deemed as an obstacle and is hidden, and the fact that the obstacle has been hidden is notified to the user. According to this technique, a positional relationship between a surgical site and an obstacle can be clarified and, at the same time, the user can readily observe the surgical site.
However, in Patent Document 1, surgical sites that are desirably constantly displayed as observation objects are set in advance, and all obstacles are uniformly hidden regardless of whether or not the user makes a move such as coming into contact with a surgical site. Therefore, Patent Document 1 is problematic in that obstacles cannot be switched between displayed and hidden modes in accordance with moves made by the user's will in response to changes in the state of a real object. As a result, even if the technique disclosed in Patent Document 1 is applied to an augmented reality space in which a virtual object is displayed, visibility of a real object cannot be improved while imparting a sense of presence unique to the augmented reality space to a user.
Patent Document 1: Japanese Patent Application Laid-open No. 2008-029694